Environmental chamber

ABSTRACT

An environmental chamber for maintaining a stabilized gas mixture environment about the head portion of a patient disposed therein formed by a chamber having peripheral side walls and an open bottom end and bounded by a closed top wall, a patient receiving opening in the side walls bounded by substantially parallel sides, a gas inlet disposed adjacent the top wall of the chamber, a gas baffle associated with the gas inlet and constructed to baffle the gas entering therein upwardly against the closed top wall and down about the head portion of a patient, and a closure member for closing off the patent receiving opening during use.

United States Patent [19] Heath ENVIRONMENTAL CHAMBER [75] Inventor: Walter Heath, Chicago, Ill.

[73] Assignee: Parkland International lnc., Melrose Park, Ill.,

[22] Filed: July 28, 1972 21 Appl. No.1 276,255

[52] US. Cl 128/191 A [51] Int. Cl A6lm 16/02 [58] Field of Search 128/191, 191 A, 194, 203,

[ Mar. 26, 1974 Godula & Demeur [5 7] ABSTRACT An environmental chamber for maintaining a stabilized gas mixture environment about the head portion of a patient disposed therein formed by a chamber having peripheral side walls and an open bottom end and bounded by a closed top wall, a patient receiving opening in the side walls bounded by substantially parallel sides, a gas inlet disposed adjacent the top wall of the chamber, a gas baffle associated with the gas inlet [56] References Cited and constructed to baffle the gas entering therein up UNITED T PATENTS wardly against the closed top wall and down about the 3,000,379 9/1961 Viers 128/191 head portion of a patient and a clo ure member for closing off the patent receiving opening during use. ea Oll 6 Claims, 4 Drawing Figures v 44 ||!"H||l-' i 'i' l v 54 \H v [in iU/H I l t y- Mllllll J y p i 3 5s :v 1 2 1 N l 42 I A ea 5 I 13%". "Y 66 a; M; m W i a n A m F {k a lt /l l I Wit v, [I 1]1), l J .ra: I l 'r "fk a I" vi Nut j I n I w I I 1 t I t x: I 1 5 v! I ...|1||Illl||llllmmlmnmmlmlllllllllnunm...

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mnllllillllill llllllllllllll 1. ENVIRONMENTAL CHAMBER BACKGROUND OF THE INVENTION Various types of devices and structures are presently in use for providing a substantially closed environmental chamber for the purpose of maintaining a particular gas environment for a patient. For example, the most common form of such chamber would consist of an oxygen tent placed about the head and/or complete body of a patient, the oxygen tent in effect providing a closed environment about the patient and the environment consisting of an oxygen rich gas atmosphere The most common construction consists of a plasticized curtain which is suspended over the patient while reclined in a hospital bed or the like, the curtain being closed about all sides, the top and being draped over the bed thereby to provide an effectively closed off environment.

It will be appreciated that one of the difficulties which has arisen with such constructions resides first of all in the bulk and size of such devices, thereby requiring a great deal of space in order to erect and maintain the structure as well as in the cost incident to'manufacturing, maintaining and using such bulky structures. For example, with such structures as an oxygen tent of the type described above, it is clear that it would be necessary to supply a great deal of oxygen in order to completely fill the volume created by the tent resulting in a situation where more than the needed amount of oxygen is utilized per patient. In addition, access to the patient by attending physicians or other help, is rendered difficult, since it would be necessary to remove a goodly portion of the tent in order to gain access to the patient. From the standpoint of cost, it is clearly apparent that the hospital must not only purchase the oxygen tent per se but it is necessary to have various types of supporting structures in order to adequately suspend the tent overhead and permit the tent to then drape downwardly to form a closed environment.

Various forms of such tent constructions are shown in the prior patented art. For example, U.S. Pat. No. 1,892,378 shows one form of such a tent structure wherein a bed is completely encased by a cubicle tent, the rear portion of the tent being slidably engageable with the forwardportion thereby to permit the opening and closing thereof. The problems noted above with respect to the standard type oxygen tent are clearly applicable with respect to the structure disclosed in the U.S. Pat. No. 1,892,378. For example, in supplying oxygen or any other gas atmosphere to the patientenclosed within the tent structure, it is necessary to completely fill the closed environment for the patient to obtain the benefits of the gas atmosphere. In addition, clearly the device illustrated in the aforementioned patent is bulky and would represent a considerable expense to a hospital or other institution having such devices, since a number of these devices must be purchased and be available for several patents.

From the standpoint of portability, various other attempts have been made to design hoods for patients requiring a stabilized gas atmosphere. French Pat. No. 928,602 illustrates one form of an infant patient hood which is somewhat portable and which is so designed as to be placed completely over the patient as to encase the patient completely after which the gas atmosphere required is supplied. Clearly, such structures have limited applicability since if the structure is large enough to accommodate only an infant, it is not useful for an adult patient. On the other hand, to construct such an enclosure for an adult patient would require that the structure be substantially as large as the bed upon which the patient is reclined. This again leads to the drawback of bulkiness, and expense as well as the storage problem for the hospital or institution which is required to keep a number of such devices on hand.

A more recent attempt at a portable hood is illustrated in U.S. Pat. No. 3,552,391 which issued to David D. Deaton on Jan. 5, 1971. The aforementioned patent illustrates a portable patient hood especially adapted for infant use which is basically formed as a cylindrical tube having open top and bottom ends and patient receiving opening for receiving the head of a patient therein. A gas inlet is provided adjacent the lower end of the hood and the gas inlet has a T-tube associated therewith in order to propel the gas along the side walls of the hood thereby creating a vortex flow of gas within the hood for the benefit of the patient. According to the teaching of the patent the structure disclosed therein relies upon the side walls of the hood in order to achieve a vortex flow of the gas within the hood and to thereby completely envelope the patient with the necessary gas atmosphere. I

The structure noted in the U.S. Pat. No. 3,552,391, however, has various drawbacks and undesirable features associated therewith. For example, the patient receiving opening disclosed therein consists of a semicircular opening having a curtain attached thereto. It has been found that when the hood structure disclosed therein is placed over the head of a patient the semicircular patient receiving opening will bind and rub against the shoulders of the patient creating discomfort and binding against the body of the patient. Furthermore, due to the size of the structure as a whole, as well as the patient receiving opening, the hood has limited applicability with respect to the size of the patient in connection with which the hood is being utilized. Even more importantly, as mentioned above, the patent teaches that the gas inlet is located adjacent the bottom portion of the hood and due to the T-shaped valve associated with the gas inlet, the gas is caused to be propelled along the side walls of the hood and create a vortex flow path for the gas. In other words, the gas flow is rather turbulent within the walls of the hood and this appears to be required in order to ensure that the patient is receiving the proper oxygen content. However, due to the fact that the hood is open topped, an effective oxygen-air gas mixture cannot be assured. Hence, while the precise level of oxygen which is deemed necessary for a particular patient may be regulated with respect to the gas entering into the gas inlet, due to the open top feature, either too much or too little air is likely to mix with the oxygen thereby rendering it virtually impossible to obtain a closely regulated oxygen-air gas mixture. Also associated with the aforementioned problem is the fact that as mentioned above, the particular vortex flow of gas created by the structure as a whole, with the gas inlet disposed as indicated, does create a rather turbulent gas flow within the chamber. Should the patient be suffering from an ailment such as a common cold or other ailments whereby it would be less than desirable for the patient to be confronted with violent or turbulent gas striking the patient's face, such a structure could not be utilized with such a patient.

SUMMARY OF INVENTION The present invention provides a portable environmental chamber useful for maintaining a stabilized gas environment about the head portion of a patient which eliminates the problems noted with respect to the prior art device while at the same time maximizing the beneficial effects deemed to be desirable with such structures. The present environmental chamber is formed from a substantially closed chamber having a closed top wall, and a gas inlet positioned adjacent the top portion of the chamber and having a gas baffle associated with the gas inlet to baffle the entering gas upwardly against the closed top wall causing the gas to strike the top wall and drift downwardly slowly thereby to eliminate gas turbulence within the chamber and envelope the head of the patient. In this manner, the hood of the present invention results in a more closely regulated oxygen-air gas mixture, at the same time ensuring that the patient is receiving a constant flow of gas.

The present invention also seeks to provide an environmental chamber wherein the patient receiving opening is enlarged so as to eliminate any problem of the hood binding or rubbing against the shoulder or upper torso portion of the patient when disposed under the hood.

The principal object of this invention is therefore a portable environmental chamber for maintaining a stabilized gas environment about the head portion of a patient wherein the chamber is formed by peripheral side walls having an open bottom and a substantially closed top end, a gas inlet positioned adjacent to the top end of the chamber and gas baffle associated with the gas inlet for baffling the entering gas upwardly against the closed top end causing the gas to strike the top walls and drift slowly downwardly about the head portion of the patient, and an enlarged patient receiving opening bounded by substantially parallel side walls, whereby the patient may be more comfortably disposed within the hood, without causing any binding or rubbing effects of the chamber with respect to the body of the patient.

Still another object of this invention is to provide an environmental chamber of the type described above, wherein the top wall includes a single opening thereby to provide a venting function as well as to permit patient access by an attending physician or another attendant.

Yet a further object of the present invention is to provide an environmental chamber of the type described, wherein a removable head rest is provided interiorly of the chamber and disposed across the interior portion of the chamber whereby the patients head is more accurately positioned internally of the chamber, the head rest preventing the hood from sliding down over the patient, or preventing the patients head from sliding upwardly against the back wall of the chamber, thereby to prevent binding of the chamber against the head of the patient, while at the same time accurately positioning the head of the patient within the chamber to achieve the maximum benefit from the flow of oxygenair gas as the same enters into and fills the environmental chamber with the desired gas.

In connection with the foregoing objects, it is still another object of this invention to provide an environmental chamber of the type described wherein the gas baffle comprises a removable open top cylindrical member and having a substantially closed bottom wall whereby gas entering into the gas baffle is caused to strike the cylindrical side walls and be forced upwardly out of the gas baffle and into striking contact with the closed top wall of the chamber, thereby to reduce the velocity of the gas and cause the gas to drift slowly downwardly over the head of the patient.

Further features of the invention pertain to the particular arrangement of the parts whereby the aboveoutlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanying drawings in which:

FIG. 1 is a front perspective view showing the environmental chamber of the present invention with an infant patient positioned thereunder;

FIG. 2 is a rear perspective view showing the environmental chamber of the present invention including the gas inlet and substantially closed top wall;

FIG. 3 is a top cross-sectional view showing the environmental chamber of the present invention, including the removable head rest positioned therein in relation to the head of the patient positioned under the chamber, and the gas baffle positioned in association with the gas inlet; and

FIG. 4 is a side elevational cross-sectional view showing the environmental chamber of the present invention positioned about the patient and showing the removable head rest in position and also showing the gas baffle associated with the gas inlet for baffling the gas upwardly, whereby the gas strikes the closed top wall and drifts downwardly about the head of the patient.

Referring now to the drawings, the environmental chamber of the present invention is generally referred to by the numeral 10. The chamber 10 includes a rear portion generally referred to by the numeral 12, a front portion generally referred to by the numeral 14, side portions referred to by the numerals 16 and 18 respectively, and a top portion generally referred to by the numeral 20. A rear portion 12 and side portions 16 and 18 respectively are formed by a coextensive of peripheral side wall 22 which is substantially semi-circular in configuration, the peripheral side wall 22 forming the rear portion 12 and the side portions 16 and 18. Each of the side portions 16 and 18 terminate in straight side walls 24 and 26 respectively, the straight side walls 24 and 26 being substantially parallel one with respect to the other.

The leading edges of the straight side walls 24 and 26 form a patient receiving opening 28, having a length dimension substantially equal to the diameter formed by the semi-circular peripheral side wall 22. The height dimension of the patient receiving opening 28 is approximately one-half of the overall height of the chamber 10 and is bounded by a lip 30 extending generally from the side edges of the two straight side walls 26 and 28 and being joined to the peripheral side wall 22 by means of opposed platforms 32 and 34 respectively.

The top portion 20 is formed by a top wall 36 which is substantially circular in configuration and has a diameter substantially equal to the diameter formed by the semi-circular peripheral side wall 22. The top wall 36 is joined to the top edge of the peripheral side wall 22 in secured relation such that the top wall 36 is not removable. The top wall is further provided with an enlarged vent opening 38 which is'positioned adjacent the front portion 14 of the chamber 10. The vent opening 38 is further so positioned as to be substantially directly over the head of a patient when a patient is positioned within the chamber 10.

As shown in FIGS. 2, 3 and 4 of the drawings, the rear portion 12 is provided with an aperture 40 which functions as a gas inlet. A gas baffle 42 is provided, the gas baffle 42 having a shank 44 which is cylindrical in configuration and has a diameter substantially equal to the diameter of the aperture 40. The shank 44 terminates at its inner end in an open topped cup baffle 46, the cup baffle 46 being formed by cylindrical side wall 48, and a closed bottom 50. In the preferred embodiment, the closed bottom wall 50 is provided with a vent 52 which functions as an escape opening for any particulate matter which may be entrained in the air or gas mixture entering into the cup baffle 46.

In use, the gas baffle 42 is fitted into the aperture 40 in the rear portion 12 of the chamber adjacent the top portion thereof by inserting the shank 44 through the aperture 40. As mentioned above, since the diameter of the shank 44 is substantially equal to the diameter of the aperture 40, a very tight friction fit may be achieved between the elements. The gas baffle 42 is inserted with the open-topped cup baffle 46 positioned interiorly of the chamber 10 with the shank 44 extending outwardly through the rear portion 12 of the chamber 10. The cup baffle 46 is positioned with the open end facing the undersurface of the top wall 36 and the enclosed bottom wall 30 facing downwardly. A gas hose 54 is fitted over the free end of the shank 44 extending out from the chamber 10, the diameter of the gas hose 54 being substantially equal to the diameter of the shank 44 whereby a tight friction fit is obtained. As is customary in such connections the shank 44 may be provided with a peripheral bead 56 to further ensure that the gas hose 54, when inserted over the shank 44 will achieve a fluid tight seal.

As shown in FIGS. 3 and 4 of the drawings, a removable head rest assembly 58 is provided, the head rest assembly 58 consisting of a substantially flexible band 60 provided with fastening means 62 at its-opposed edges. The interior surface of the peripheral side wall 22 is similarly provided with mating fastening means 64, the fastening means 62 and mating fastening means 64 being removably engageable with respect to one another. In this manner, the flexible band 60 may be easily and efficiently positioned within the interior of the chamber 10 when desired, and may be similarly efficiently and easily removed when not required or desired by simply disengaging the fastening means 62 from the mating fastening means 64.

As is shown in both FIGS. 3 and 4 of the drawings, the flexible band 60 when fastened within the interior of the chamber 10 will generally tend to form a semicircular arc spaced inwardly from the rear portion 12 of the chamber 10. In this manner, the head of the patient positioned within the chamber 10 will be prevented from sliding back against the rear portion 12 in the chamber 10, thereby preventing any binding or rubbing effect as between the top portion of the patients head and the interior surface of the peripheral side wall 22 adjacent the rear portion 12 thereof. In addition the band 60 ensures that the patients head will be positioned forwardly of the gas baffle 42 in order to obtain to maintain a substantially closed environment within the chamber 10.

The only opening provided for the chamber 10 when in use is the enlarged vent opening 38 positioned in the top wall 36. The vent opening 38 serves the dual function of permitting-air to enter into the chamber 10 while at the same time permitting the elimination of carbon dioxide gases as the patient breathes within the chamber 10. The important consideration with regard to the vent opening 38 is the fact that it is positioned forwardly of the rear portion 12 such as to be in a direct vertical line over the head of the patient when positioned within the chamber 10 and is large enough to permit the insertion of an attendants hands therethrough to, say for example, adjust the positioning of the patients head, while still being sufficiently small so as to provide a basically closed top wall 36.

In operation, a gas mixture such as oxygen-air, is fed from a source through the gas hose 54 and then into the shank portion 44 of the gas baffle 42. The pathway through the shank 44 leads into the open topped cup baffle 46, where the gas mixture is caused to strike the interior surface of the cylindrical side wall 48 thereof. In view of the fact that the bottom wall 50 is closed, save for the vent 52, the gas entering into the cup baffle 46 will be forced upwardly striking the under surface of the top wall 36. As indicated by the arrows in FIG. 4 of the drawings, once the gas has struck the undersurface of the top wall 36, the velocity of the gas is materially reduced thereby, in effect, causing the gas to drift downwardly and envelope the patients head positioned thereunder. Hence, the relative slow drifting wall of gas completely fills the chamber-l0 and provides the patient with a constant and non-turbulent supply of oxygen-air gas mixture. Due to the novel method of baffling the gas as the same enters into the chamber 10, the patient is spared a blast of turbulent air or gas passing about and over his head and upper torso region.

It will therefore be appreciated that one of the key features of the present invention is the provision of a gas baffle disposed adjacent to the top of the hood, in combination with a closed, or substantially closed top whereby the gas baffled upwardly will strike the top causing a reduction in the velocity of the gas and permit the gas to fall slowly upon and around the patients head.

The principal function served by the head rest assembly 58 is two-fold in that it positions the patients head substantially in the central portion of the chamber 10 while at the same time preventing the chamber 10 from sliding down and resting against the patients head. This is an especially useful feature since in many applications the environmental chamber 10 is utilized on a patient while he is positioned on a hospital bed with the upper portion of the bed in an inclined position. Clearly, if the chamber 10 is positioned on an inclined surface such as an inclined hospital bed, the normal tendency would be for the hood to slide downwardly until the patients head is resting against the rear surface of the chamber. With reference to the prior art and more particularly, US. Pat. No. 3,552,391, clearly the chamber disclosed therein having no head rest and having the gas inlet position adjacent the lower portion of the chamber would cause great discomfort as well as diminishing the beneficial effects to be achieved from the use of such a chamber. Undoubtedly a chamber of the type disclosed in the aforementioned patent could not be utilized on an inclined surface for this very reason.

In the preferred embodiment, the chamber 10 formed by the rear portion 12, front portion 14 and side portions 16 and 18 respectively, are formed of a plastic material such as polyethylene or polyproplyene, or the like. Furthermore, in the whole unit consisting of the aforementioned portions, may be molded such as by an injection molded process as a unitary body. The top portion 20 consisting of the top wall 36, could be molded as a separate element and then, fixedly secured to the top peripheral edge of the peripheral side wall 22. Hence, the top wall 36 may be securely fixed by such means as epoxy resin adhesives, heat sealing means, or the like.

The gas baffle 42 would be provided as a separate piece and as indicated above, is formed by a shank 44 and an open topped cup baffle 46. The shank 44 and cup baffle 46 are, once again, formed as a unitary piece and may be molded of a plastic material as is known in the art.

The two remaining elements necessary for the completion of the construction of the environmental chamber 10 include the flexible band 60 and the curtain 66. The flexible band 60 is preferably formed ofa soft polyethylene plastic material whereby the band 60 may conform to the head of the patient, if and when the patients head moves up against the band 60. In this manner discomfort and binding of the band 60 against the head of the patient is minimized for maximum patient comfort.

The curtain 66 may be formed of any flexible material, either plastic or cloth, which permits the operator or attendant to physically raise the curtain until the patient has been positioned under the chamber 10 after which the curtain is dropped to cover the head and upper chest portions of the patient. FIGS. 1 and 4 of the drawings illustrate the manner in which the curtain 66 falls about the body portion of the patient.

It is contemplated to be within the scope of the present invention to form the environmental chamber 10 as described above of a completely disposable plastic material. It is apparent that there is no particular need or requirement that the complete structure be formed of a heavy or rigid material, since no part of the chamber 10 is load bearing in any sense. Perhaps the only area which would have to be strengthened would be the area surrounding the aperture 40, since the aperture 40 must carry the gas baffle 42, which in turn, is connected to the gas hose 54. In any event, it is contemplated that with the development of newer plastic materials, the entire structure could be molded of a very lightweight plastic and therefore, be provided to a hospital or other institution in a sterilized pre-packaged form.

It will be apparent from the above description that the environmental chamber described herein achieves all of the objects and advantages set forth. The environmental chamber described above provides a substantially closed chamber which thereby permits a more closely regulated control of the gas mixture deposited in the interior of the chamber. In addition, due to the novel gas baffling system provided herein, the velocity of the gas is slowed down prior to touching contact with the patients head, thereby to ensure that the patient will be completely enveloped by the gas mixture and to further prevent gas turbulence from causing discomfort to the patient during use. Finally, it will also be observed that the enlarged patient receiving opening forming a part of the chamber structure as described herein permits a wider application of use with respect to patients of different sizes, as well as to prevent any binding or rubbing which may occur as between the patient entrance opening and the patients shoulders or head region.

While there has been described what at present is considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A portable environmental chamber useful for maintaining a stabilized gas environment about the head and shoulders of a patient comprising in combination,

a chamber formed by peripheral side walls and having an open bottom end and bounded by a substantially closed top wall,

vent means provided in said top wall and positioned in substantially vertical alignment with the head of a patient disposed within the chamber during use,

a patient receiving opening in said peripheral side walls, said opening bounded by substantially parallel sides,

a gas inlet disposed in a portion of said peripheral side walls in opposed relation with respect to said patient receiving opening and'positioned adjacent said top wall,

a gas baffle immediately surrounding said gas inlet and mounted on said peripheral side wall and positioned adjacent said top wall and rearward of said vent means interiorly of said chamber,

said gas baffle formed by surrounding side walls and a bottom wall and having an open top so as to baffle gas entering therein upwardly against said top wall,

and a removable closure member for said patient receiving opening for substantially closing said opening during use,

whereby a gas entering said chamber through said gas inlet is baffled upwardly by said gas baffle to strike against said closed top wall reducing the velocity of Y the gas and causing the gas to drift slowly downwardly about the head of a patient disposed within said chamber while said closure member is positioned to close off said patient receiving opening and retain said gaseous environment within said chamber during use, while said vent means and said top wall permits the inflow of environmental air and the outflow of carbon dioxide.

2. The portable environmental chamber as set forth in claim 1 above, wherein said vent means comprises a circular opening in said top wall having a diameter sufficiently large so as to permit the insertion and removal of an attendants hand to permit patient adjustment during use.

3. The portable environmental chamber as set forth in claim 1 above, which further includes a removable head rest assembly disengageably mounted across said peripheral side walls interiorly of said chamber and spaced intermediate said patient receiving opening and said gas baffle thereby to restrain a patients head from movement within said chamber during use.

4. The portable environmental chamber as set forth in claim 1 above, wherein said gas baffle comprises an open topped cylindrical member having the shank portion extending exteriorly of said chamber, and an open topped cup baffle positioned interiorly of said chamber, said open topped cup baffle having a substantially closed bottom wall whereby gas entering said gas baffle through said gas inlet must follow a gas pathway upwardly thereby to strike against said closed top wall whereby the gas velocity will be reduced and the gas will drift slowly downwardly to envelope the head of a patient disposed within said chamber.

5. The portable environmental chamber as set forth in claim 4 above, wherein said gas baffle further includes a vent opening disposed in said bottom wall thereof for facilitating the removal of any foreign particles entrained in the gas.

6. The portable environmental chamber as set forth in claim 1 above, wherein said chamber is substantially semi-circular in configuration and terminates in substantially parallel side walls along the front portion thereof, said substantially parallel side walls forming an enlarged patient receiving opening therebetween, said patient receiving opening being sufficiently wide so as to accommodate the head and upper torso portion of a patient disposed therein. 

1. A portable environmental chamber useful for maintaining a stabilized gas environment about the head and shoulders of a patient comprising in combination, a chamber formed by peripheral side walls and having an open bottom end and bounded by a substantially closed top wall, vent means provided in said top wall and positioned in substantially vertical alignment with the head of a patient disposed within the chamber during use, a patient receiving opening in said peripheral side walls, said opening bounded by substantially parallel sides, a gas inlet disposed in a portion of said peripheral side walls in opposed relation with respect to said patient receiving opening and positioned adjacent said top wall, a gas baffle immediately surrounding said gas inlet and mounted on said peripheral side wall and positioned adjacent said top wall and rearward of said vent means interiorly of said chamber, said gas baffle formed by surrounding side walls and a bottom wall and having an open top so as to baffle gas entering therein upwardly against said top wall, and a removable closure member for said patient receiving opening for substantially closing said opeNing during use, whereby a gas entering said chamber through said gas inlet is baffled upwardly by said gas baffle to strike against said closed top wall reducing the velocity of the gas and causing the gas to drift slowly downwardly about the head of a patient disposed within said chamber while said closure member is positioned to close off said patient receiving opening and retain said gaseous environment within said chamber during use, while said vent means and said top wall permits the inflow of environmental air and the outflow of carbon dioxide.
 2. The portable environmental chamber as set forth in claim 1 above, wherein said vent means comprises a circular opening in said top wall having a diameter sufficiently large so as to permit the insertion and removal of an attendant''s hand to permit patient adjustment during use.
 3. The portable environmental chamber as set forth in claim 1 above, which further includes a removable head rest assembly disengageably mounted across said peripheral side walls interiorly of said chamber and spaced intermediate said patient receiving opening and said gas baffle thereby to restrain a patient''s head from movement within said chamber during use.
 4. The portable environmental chamber as set forth in claim 1 above, wherein said gas baffle comprises an open topped cylindrical member having the shank portion extending exteriorly of said chamber, and an open topped cup baffle positioned interiorly of said chamber, said open topped cup baffle having a substantially closed bottom wall whereby gas entering said gas baffle through said gas inlet must follow a gas pathway upwardly thereby to strike against said closed top wall whereby the gas velocity will be reduced and the gas will drift slowly downwardly to envelope the head of a patient disposed within said chamber.
 5. The portable environmental chamber as set forth in claim 4 above, wherein said gas baffle further includes a vent opening disposed in said bottom wall thereof for facilitating the removal of any foreign particles entrained in the gas.
 6. The portable environmental chamber as set forth in claim 1 above, wherein said chamber is substantially semi-circular in configuration and terminates in substantially parallel side walls along the front portion thereof, said substantially parallel side walls forming an enlarged patient receiving opening therebetween, said patient receiving opening being sufficiently wide so as to accommodate the head and upper torso portion of a patient disposed therein. 